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Publications of The Korean Astronomical Society
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The Korean Astronomical Society
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Volume & Issues
Volume 27, Issue 5 - Dec 2012
Volume 27, Issue 4 - Sep 2012
Volume 27, Issue 3 - Jul 2012
Volume 27, Issue 2 - Jun 2012
Volume 27, Issue 1 - Mar 2012
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AKARI-FIS POINT SOURCE CATALOGUE: CURRENT STATUS AND FUTURE PLAN
Yamamura, Issei ; Makiuti, Sin'itirou ; Ikeda, Norio ; Koga, Tatsuya ; Yoshino, Akira ; Yamauchi, Chisato ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 105~109
DOI : 10.5303/PKAS.2012.27.4.105
The current status of the AKARI-FIS Point Source Catalogue is reported. The first version of the Bright Source Catalogue has been in public since March 2010 and used extensively in the various fields in astronomy. The second version of the Bright Source Catalogue and the first version of the Faint Source Catalogue are currently under development. The revised Bright Source Catalogue is expected to have improved completeness, reliability, and accuracy compared to the current version. The Faint Source Catalogue will have a scan-density dependent detection limit and will enable much deeper exploration of the sky especially in the high-ecliptic latitude regions. Both catalogues will be available in a year time scale.
AKARI FAR-INFRARED ALL-SKY SURVEY MAPS
Doi, Yasuo ; Komugi, Shinya ; Kawada, Mitsunobu ; Takita, Satoshi ; Arimatsu, Ko ; Ikeda, Norio ; Kato, Daisuke ; Kitamura, Yoshimi ; Nakagawa, Takao ; Ootsubo, Takafumi ; Morishima, Takahiro ; Hattori, Makoto ; Tanaka, Masahiro ; White, Glenn J. ; Etxaluze, Mireya ; Shibai, Hiroshi ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 111~116
DOI : 10.5303/PKAS.2012.27.4.111
Far-infrared observations provide crucial data for the investigation and characterisation of the properties of dusty material in the Interstellar Medium (ISM), since most of its energy is emitted between ~ 100 and
. We present the first all-sky image from a sensitive all-sky survey using the Japanese AKARI satellite, in the wavelength range
. Covering > 99% of the sky in four photometric bands with four filters centred at
wavelengths, this achieved spatial resolutions from 1 to 2 arcmin and a detection limit of < 10 MJy
, with absolute and relative photometric accuracies of < 20%. All-sky images of the Galactic dust continuum emission enable astronomers to map the large-scale distribution of the diffuse ISM cirrus, to study its thermal dust temperature, emissivity and column density, and to measure the interaction of the Galactic radiation field and embedded objects with the surrounding ISM. In addition to the point source population of stars, protostars, star-forming regions, and galaxies, the high Galactic latitude sky is shown to be covered with a diffuse filamentary-web of dusty emission that traces the potential sites of high latitude star formation. We show that the temperature of dust particles in thermal equilibrium with the ambient interstellar radiation field can be estimated by using
data. The FIR AKARI full-sky maps provide a rich new data set within which astronomers can investigate the distribution of interstellar matter throughout our Galaxy, and beyond.
LIFECYCLE OF THE INTERSTELLAR DUST GRAINS IN OUR GALAXY VIEWED WITH AKARI/MIR ALL-SKY SURVEY
Ishihara, D. ; Kaneda, H. ; Mouri, A. ; Kondo, T. ; Suzuki, S. ; Oyabu, S. ; Onaka, T. ; Ita, Y. ; Matsuura, M. ; Matsunaga, N. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 117~122
DOI : 10.5303/PKAS.2012.27.4.117
The interstellar dust grains are formed and supplied to interstellar space from asymptotic giant branch (AGB) stars or supernova remnants, and become constituents of the star- and planet-formation processes that lead to the next generation of stars. Both a qualitative, and a compositional study of this cycle are essential to understanding the origin of the pre-solar grains, the missing sources of the interstellar material, and the chemical evolution of our Galaxy. The AKARI/MIR all-sky survey was performed with two mid-infrared photometric bands centered at 9 and
. These data have advantages in detecting carbonaceous and silicate circumstellar dust of AGB stars, and the interstellar polycyclic aromatic hydrocarbons separately from large grains of amorphous silicate. By using the AKARI/MIR All-Sky point source catalogue, we surveyed C-rich and O-rich AGB stars in our Galaxy, which are the dominant suppliers of carbonaceous and silicate grains, respectively. The C-rich stars are uniformly distributed across the Galactic disk, whereas O-rich stars are concentrated toward the Galactic center, following the metallicity gradient of the interstellar medium, and are presumably affected by the environment of their birth place. We will compare the distributions of the dust suppliers with the distributions of the interstellar grains themselves by using the AKARI/MIR All-Sky diffuse maps. To enable discussions on the faint diffuse interstellar radiation, we are developing an accurate AKARI/MIR All-Sky diffuse map by correcting artifacts such as the ionising radiation effects, scattered light from the moon, and stray light from bright sources.
OVERVIEW OF THE NORTH ECLIPTIC POLE DEEP MULTI-WAVELENGTH SURVEY (NEP-DEEP)
Matsuhara, H. ; Wada, T. ; Takagi, T. ; Nakagawa, T. ; Murata, K. ; Churei, S. ; Goto, T. ; Oyabu, S. ; Takeuchi, T.T. ; Ohyama, Y. ; Miyaji, T. ; Krumpe, M. ; Lee, H.M. ; Im, M. ; Serjeant, S. ; Peason, C.P. ; White, G. ; Malkan, M.A. ; Hanami, H. ; Ishigaki, T. ; Burgarella, D. ; AKARI NEP Team, AKARI NEP Team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 123~128
DOI : 10.5303/PKAS.2012.27.4.123
An overview of the North Ecliptic Pole (NEP) deep multi-wavelength survey covering from X-ray to radio wavelengths is presented. The main science objective of this multi-wavelength project is to unveil the star-formation and AGN activities obscured by dust in the violent epoch of the Universe (z=0.5-2), when the star formation and black-hole evolution activities were much stronger than the present. The NEP deep survey with AKARI/IRC consists of two survey projects: shallow wide (8.2 sq. deg, NEP-Wide) and the deep one (0.6 sq. deg, NEP-Deep). The NEP-Deep provides us with a
selected sample of several thousands of galaxies, the largest sample ever made at these wavelengths. A continuous filter coverage at mid-IR wavelengths (7, 9, 11, 15, 18, and
) is unique and vital to diagnose the contribution from starbursts and AGNs in the galaxies at the violent epoch. The recent updates of the ancillary data are also provided: optical/near-IR magnitudes (Subaru, CFHT), X-ray (Chandra), FUV/NUV (GALEX), radio (WSRT, GMRT), optical spectra (Keck/DEIMOS etc.), Subaru/FMOS, Herschel/SPIRE, and JCMT/SCUBA-2.
NORTH ECLIPTIC POLE WIDE SURVEY
Lee, Hyung Mok ; Kim, Seong Jin ; NEP-Wide Team, NEP-Wide Team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 129~134
DOI : 10.5303/PKAS.2012.27.4.129
The North Ecliptic Pole (NEP) Wide survey covered about 5.4
, a nearly circular area centered on the NEP, using nine passbands of InfraRed Camera (IRC). We present the photometric properties of the data sets, and the nature of the sources detected in this field. The number of detected sources varied according to the filter band: with about 109,000 sources in the NIR, about 20,000 sources in the MIR-S, and about 16,000 sources seen in the MIR-L channel. The
detection limits are about 21 mag in the NIR and 19.5 - 18.5 mag in the MIR bands in terms of the AB magnitude. 50% completeness levels are about 19.8 mag at
, 18.6 mag at
, and 18 mag at
band (in AB magnitude), respectively. In order to validate the detected sources, all of them are confirmed by matching tests with those in other bands. The 'star-like' sources, defined by the high stellarity and magnitude cut from the optical ancillary data, appear statistically to have a high probability of being stars. The nature of the various types of extragalactic sources in this field are discussed using the color-color diagrams of the NIR and MIR bands with the redshift tracks of galaxies providing useful guidelines.
THE AKARI DEEP FIELD SOUTH: A NEW HOME FOR MULTIWAVELENGTH EXTRAGALACTIC ASTRONOMY
Clements, David L. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 135~140
DOI : 10.5303/PKAS.2012.27.4.135
The importance of multiwavelength astronomical surveys is discussed in the context of galaxy evolution. The AKARI Deep Field South (ADF-S) is a new, well placed survey field that is already the subject of studies at a wide range of wavelengths. A number of ADF-S observational programmes are discussed and the prospects for the ADF-S as a future resource for extragalactic astronomy is explored.
FAR INFRARED GALAXIES IN AKARI'S EYE
Malek, K. ; Pollo, A. ; Takeuchi, T.T. ; Giovannoli, E. ; Buat, V. ; Burgarella, D. ; Malkan, M. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 141~144
DOI : 10.5303/PKAS.2012.27.4.141
We present the results of Spectral Energy Distribution (SED) fitting of far-infrared galaxies detected in the AKARI Deep Field-South (ADF-S) Survey and discuss their physical properties. Additionally, we perform a comparison between photometric redshifts estimated using only optical and both optical and infrared data. We conclude that our sample consists mostly of nearby galaxies rich in dust and young stars. We observe an improvement in the estimation of photometric redshifts when the IR data are included, comparing to a standard approach based mainly on the optical to UV photometry.
OPTICAL/NIR IMAGING OF AKARI NEP-WIDE SURVEY FIELD
Jeon, Yiseul ; Im, Myungshin ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 145~146
DOI : 10.5303/PKAS.2012.27.4.145
We present the results from B-, R-, I-, J- and H-band observations of the NEP-Wide survey field. The NEP-Wide survey is an AKARI survey of the North Ecliptic Pole covering ~ 5 square degrees area. Our optical/NIR imaging supports the AKARI IR imaging data by providing a crucial coverage in the optical/NIR. The optical data were obtained in 2007 using the 1.5 m telescope and SNUCAM at Maidanak Observatory, Uzbekistan. The NIR data were obtained in 2008 with FLAMINGOS on the KPNO 2.1 m telescope. We used IRAF, SExtractor, SCAMP, and SWarp for reducing the raw data, I-band fringe pattern removal, astrometry, standard photometry calibration, and source detection. Our optical-NIR data reach the depths of B ~ 23.4, R ~ 23.1, I ~ 22.3, J ~ 21.05, and H ~ 20.64 AB mag at 5-sigma. Here, we present the astrometric accuracy, galaxy number counts, completeness, and reliability, as well as redshift tracks of some normal galaxies and quasars on the B - R vs. R - I color-color diagram. The photometric data are being used for identifying optical counterparts of the IR data provided by AKARI, studying their SEDs, and selecting interesting objects for spectroscopic follow-up studies.
NEP-WIDE POINT SOURCE CATALOG
Kim, Seong Jin ; Lee, Hyung Mok ; NEP-Wide Team, NEP-Wide Team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 147~148
DOI : 10.5303/PKAS.2012.27.4.147
We present a photometric catalog of infrared (IR) sources based on the North Ecliptic Pole Wide field (NEP-Wide) survey of AKARI, which covered a 5.4
circular area centered on NEP. The catalog contains about 115,000 sources detected at the 9 IRC filter bands, comprehensively covering a wavelength range from 2 to
. This is a band-merged catalog including all of the photometry results from the supplementary optical data as well as the IRC bands. To validate a source at a given IRC band, we searched for counterparts in the other bands. The band-merging was done based on this cross-matching of the sources among the filter bands. The NIR sources without any counterpart in any other bands are finally excluded to avoid false objects.
IMPROVEMENT OF AKARI NEP-DEEP 2-24 MICRON IMAGES/CATALOGUES WITH NEW CALIBRATIONS
Murata, Kazumi ; Matsuhara, Hideo ; Takagi, Toshinobu ; Wada, Takehiko ; Oyabu, Shinki ; Oi, Nagisa ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 149~150
DOI : 10.5303/PKAS.2012.27.4.149
We have created new catalogues of AKARI/IRC
North Ecliptic Pole Deep survey through new methods of image analysis. In the new catalogues the number of false detection decreased by a factor of 10 and the number of objects detected in multiple bands increased by more than 1,500 compared to the previous work. In this proceedings the new methods of image analysis and the performance of the new catalogues are described.
A MULTICOLOR STAR-GALAXY SEPARATION FROM THE NIR AND MIR AKARI DATA
Solarz, A. ; Pollo, A. ; Takeuchi, T.T. ; Pepiak, A. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 151~152
DOI : 10.5303/PKAS.2012.27.4.151
We present the method of star/galaxy separation based on the support vector machines (SVM) in the data from the AKARI North Ecliptic Pole (NEP) Deep survey collected through nine AKARI / IRC bands from 2 to
, with a classification accuracy of 93 %.
A PANORAMIC VIEW OF THE ASTEROIDS IN THE INNER SOLAR SYSTEM WITH AKARI
Usui, F. ; Kuroda, D. ; Muller, T.G. ; Hasegawa, S. ; Ishiguro, M. ; Ootsubo, T. ; Ueno, M. ; AKARI SOSOS team, AKARI SOSOS team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 153~159
DOI : 10.5303/PKAS.2012.27.4.153
We constructed an unbiased asteroid catalog from the mid-infrared part of the All-Sky Survey with the Infrared Camera (IRC) on board AKARI. About 20% of the point source events recorded in the IRC All-Sky Survey observations were not used for the IRC Point Source Catalog in its production process because of a lack of multiple detection by position. Asteroids, which are moving objects on the celestial sphere, are included in these "residual events" We identified asteroids out of the residual events by matching them with the positions of known asteroids. For the identified asteroids, we calculated the size and albedo based on the Standard Thermal Model. Finally we had a new brand of asteroid catalog, which contains 5,120 objects, about twice as many as the IRAS asteroid catalog.
AKARI NEAR-INFRARED SPECTROSCOPIC SURVEY FOR COMETARY VOLATILES
Ootsubo, T. ; Kawakita, H. ; Kobayashi, H. ; Usui, F. ; AKARI SOSOS team, AKARI SOSOS team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 161~164
DOI : 10.5303/PKAS.2012.27.4.161
We performed a spectroscopic survey for cometary volatiles with the Infrared Camera onboard the Japanese infrared satellite AKARI. The observations were carried out in the near-infrared wavelength range in the period from 2008 June to 2010 January. In this paper, we summarize the observations and results of the AKARI survey for the mixing ratios of major volatiles in comets. We derived the
spectra of 18 comets including both Oort cloud comets and Jupiter-family comets. Prominent emission bands in the observed spectra are the fundamental vibrational bands of water (
and carbon dioxide (
. The fundamental vibrational band of carbon monoxide (CO) at
and the broad emission feature probably related to C-H bearing molecules can also be recognized around the
region in some comets. We detect
in 17 out of 18 comets, and derived gas production rate ratios of
with respect to
in 17 comets. We detect a reliable CO emission band only in three of the comets. Our data set provides the largest homogeneous database of
ratios in comets obtained so far.
AKARI IRC SURVEY OF THE LARGE MAGELLANIC CLOUD: AN OVERVIEW OF THE SURVEY AND A BRIEF DESCRIPTION OF THE POINT SOURCE CATALOG
Ita, Yoshifusa ; Kato, Daisuke ; Onaka, Takashi ; AKARI/ ; LMC survey team, AKARI/ ; LMC survey team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 165~169
DOI : 10.5303/PKAS.2012.27.4.165
We observed an area of 10
of the Large Magellanic Cloud using the Infrared Camera (IRC) onboard AKARI. The observations were carried out using five imaging filters (3, 7, 11, 15, and
) and the prism disperser (
) equipped in the IRC. This paper presents an outline of the survey project and also describes very briefly the newly compiled near- to mid-infrared point source catalog. The
limiting magnitudes are 17.9, 13.8, 12.4, 9.9, and 8.6 mag at 3.2, 7, 11, 15 and
, respectively. The photometric accuracy is estimated to be about 0.1 mag at
and 0.06 - 0.07 mag in the other bands. The position accuracy is 0.3" at 3.2, 7 and
and 1.0" at 15 and
. The sensitivities at 3.2, 7, and
are roughly comparable to those of the Spitzer SAGE LMC point source catalog, while the AKARI catalog provides the data at 11 and
, covering the near- to mid-infrared spectral range continuously.
AKARI INFRARED OBSERVATIONS OF EMBEDDED YSOs IN THE MAGELLANIC CLOUDS
Shimonishi, T. ; Onaka, T. ; Kato, D. ; Sakon, I. ; Ita, Y. ; Kawamura, A. ; Kaneda, H. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 171~175
DOI : 10.5303/PKAS.2012.27.4.171
Spectroscopic studies of extragalactic YSOs have shown a great progress in the last few years. Infrared observations with AKARI made significant contributions to that progress. In this proceeding, we are going to introduce our current research on the infrared observations of ices and dust around embedded YSOs in the Magellanic Clouds.
EVIDENCES OF EPISODIC MASS ACCRETION IN LOW-LUMINOSITY EMBEDDED PROTOSTARS
Kim, Hyo Jeong ; Evans, Neal J. II ; Dunham, Michael M. ; Lee, Jeong-Eun ; Pontoppidan, Klaus M. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 177~179
DOI : 10.5303/PKAS.2012.27.4.177
We present Spitzer IRS spectroscopy of
ice toward 19 young stellar objects (YSOs) with luminosity lower than
ice forms only at elevated temperatures, T > 20 K, and thus at higher luminosities. Current internal luminosities of YSOs with L <
do not provide such conditions out to radii of typical envelopes. Significant amounts of pure
ice would signify a higher past luminosity. We analyze
ice bending mode absorption lines in comparison to the laboratory data. We decompose pure
ice from 12 out of 19 young low luminosity sources. The presence of the pure
ice component indicates high dust temperature and hence high luminosity in the past. The sum of all the ice components (total
ice amount) can be explained by a long period of low luminosity stage between episodic accretion bursts as predicted in an episodic accretion scenario. Chemical modeling shows that the episodic accretion scenario explains the observed total
ice amount best.
DEBRIS DISKS EXPLORED BY AKARI AND IRSF
Kiriyama, Y. ; Ishihara, D. ; Nagayama, T. ; Kaneda, H. ; Oyabu, S. ; Onaka, T. ; Fujiwara, H. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 181~182
DOI : 10.5303/PKAS.2012.27.4.181
Using the AKARI mid-infrared all-sky survey catalogue, we are searching for debris disks which are important objects as an observational clue to on-going planetary system formation. Debris disk candidates are selected through a significant excess of the measured flux over the predicted flux for the stellar photospheric emission at
. The fluxes were originally estimated based on the near-infrared spectral energy distributions (SEDs) of central stars constructed from the 2MASS J-, H-, and Ks-band fluxes. However, we found that in many cases the 2MASS photometry has large errors due to saturation in the central part of a star image. Therefore we performed follow-up observations with the IRSF 1.4m near-infrared telescope in South Africa to obtain accurate fluxes in the J-, H-, and Ks-bands. As a result, we have succeeded in improving the SEDs of the central stars. This improvement of the SEDs allows us to make more reliable selection of the candidates.
NEW INSIGHT ON BROWN DWARF ATMOSPHERES REVEALED BY AKARI
Sorahana, S. ; Yamamura, I. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 183~184
DOI : 10.5303/PKAS.2012.27.4.183
We present the latest results from the Mission Program NIRLT, the NIR spectroscopic observations of brown dwarfs using the IRC on board AKARI. The near-infrared spectra in the wavelength range between 2.5 and
is especially important to study the brown dwarf atmospheres because of the presence of non-blended bands of major molecules, including
, CO at
. Our observations were carried out in the grism-mode resulting in a spectral resolution of ~ 120. In total, 27 sources were observed and 18 good spectra were obtained. We investigate the behavior of three molecular absorption bands, CO,
, in brown dwarf spectra relative to their spectral types. We find that the
band appears in the spectra of dwarfs later than L5 and CO band is seen in the spectra of all spectral types.
is detected in the spectra of late-L and T type dwarfs.
A SURVEY OF T TAURI STARS WITH AKARI
Takita, S. ; Kataza, H. ; Kitamura, Y. ; Ueno, M. ; Oyabu, S. ; Ishihara, D. ; Ita, Y. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 185~186
DOI : 10.5303/PKAS.2012.27.4.185
We have carried out a survey of T Tauri stars (TTSs) in a 1,800-square-degrees region toward the Taurus-Auriga star forming region with the AKARI Mid-Infrared All-Sky Survey. By combination of AKARI, 2MASS, and UCAC surveys, we created new criteria to chose TTS candidates. We also considered Asymptotic Giant Branch stars and galaxies, which have similar infrared colors, to separate TTSs from these sources. On the basis of our criteria, we find 27 new TTS candidates. To verify our criteria, we performed follow-up observations for them and confirmed that 23 are TTSs.
AKARI OBSERVATIONS OF THE INTERSTELLAR MEDIUM
Onaka, Takashi ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 187~193
DOI : 10.5303/PKAS.2012.27.4.187
AKARI has 4 imaging bands in the far-infrared (FIR) and 9 imaging bands that cover the near-infrared (NIR) to mid-infrared (MIR) contiguously. The FIR bands probe the thermal emission from sub-micron dust grains, while the MIR bands observe emission from stochastically-heated very small grains and the unidentified infrared (UIR) band emissions from carbonaceous materials that contain aromatic and aliphatic bonds. The multi-band characteristics of the AKARI instruments are quite efficient to study the spectral energy distribution of the interstellar medium, which always shows multi-component nature, as well as its variations in the various environments. AKARI also has spectroscopic capabilities. In particular, one of the onboard instruments, Infrared Camera (IRC), can obtain a continuous spectrum from 2.5 to
with the same slit. This allows us to make a comparative study of the UIR bands in the diffuse emission from the 3.3 to
for the first time. The IRC explores high-sensitivity spectroscopy in the NIR, which enables the study of interstellar ices and the UIR band emission at
in various objects. Particularly, the UIR bands in this spectral range contain unique information on the aromatic and aliphatic bonds in the band carriers. This presentation reviews the results of AKARI observations of the interstellar medium with an emphasis on the observations of the NIR spectroscopy.
IS THE ANOMALOUS MICROWAVE EMISSION DUE TO THE ROTATION OF INTERSTELLAR PAHS? PLANCK RESULTS: PLANCK - AKARI PROJECT
Planck Collaboration, Planck Collaboration ; Giard, M. ; Berne, O. ; Doi, Y. ; Ishihara, D. ; Joblin, Ch. ; Kaneda, I. ; Marshall, D. ; Nakagawa, T. ; Ohsawa, R. ; Onaka, T. ; Sakon, I. ; Shibai, H. ; Ysard, N. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 195~200
DOI : 10.5303/PKAS.2012.27.4.195
We show how the rotation emission from isolated interstellar Polycyclic Aromatic Hydrocarbons (PAHs) can explain the so-called anomalous microwave emission (AME). AME has been discovered in the last decade as microwave interstellar emission (10 to 70 GHz) that is in excess compared to the classical emission processes: thermal dust, free-free and synchrotron. The PAHs are the interstellar planar nano-carbons responsible for the near infrared emission bands in the 3 to 15 micron range. Theoretical studies show that under the physical conditions of the interstellar medium (radiation and density) the PAHs adopt supra-thermal rotation velocities, and consequently they are responsible for emission in the microwave range. The first results from the PLANCK mission unexpectedly showed that the AME is not only emitted by specific galactic interstellar clouds, but it is present throughout the galactic plane, and is particularly strong in the cold molecular gas. The comparison of theory and observations shows that the measured emission is fully consistent with rotation emission from interstellar PAHs. We draw the main lines of our PLANCK-AKARI collaborative program which intends to progress on this question by direct comparison of the near infrared (AKARI) and microwave (PLANCK) emissions of the galactic plane.
THE FILAMENTARY WEB OF STAR FORMATION
White, Glenn J. ; Doi, Yasuo ; Komugi, Shinya ; Kawada, Mitsunobu ; Takita, Satoshi ; Arimatsu, Ko ; Ikeda, Norio ; Kato, Daisuke ; Kitamura, Yoshimi ; Nakagawa, Takao ; Ootsubo, Takafumi ; Morishima, Takahiro ; Hattori, Makoto ; Tanaka, Masahiro ; Etxaluze, Mireya ; Shibai, Hiroshi ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 201~207
DOI : 10.5303/PKAS.2012.27.4.201
Following the first Public Release of the AKARI Point Source catalogues, we have worked on the production of a new far-infrared All-Sky Diffuse mapping product. In this paper we report first results from the All Sky diffuse maps that will shortly be released to the community, based on analysis of data from the Far Infrared Surveyor (
) instrument. These data are likely to have a strong impact on studies of extended structures, and the diffuse ISM.
NEAR- TO MID-INFRARED SLIT SPECTROSCOPIC OBSERVATIONS OF THE UNIDENTIFIED INFRARED BANDS IN THE LARGE MAGELLANIC CLOUD
Mori, T.I. ; Sakon, I. ; Onaka, T. ; Umehata, H. ; Kaneda, H. ; Ohsawa, R. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 209~212
DOI : 10.5303/PKAS.2012.27.4.209
We present the results of the near-infrared (NIR) to mid-infrared (MIR) slit spectroscopic observations of the diffuse emission toward nine positions in the nearby irregular galaxy Large Magellanic Cloud (LMC) with the Infrared Camera (IRC) on board AKARI. The unique characteristic of AKARI/IRC provides a great opportunity to analyze variations in the unidentified infrared (UIR) bands based on continuous spectra from 2.5 to
of the same slit area. The observed variation of
suggests destruction of small-sized UIR band carriers, polycyclic aromatic hydrocarbons (PAHs) in harsh environments. This result demonstrates that the UIR
band provides us powerful information on the excitation conditions and/or the size distribution of PAHs, which is of importance for understanding the evolutionary process of hydrocarbon grains in the Universe. It also suggests a new diagnostic diagram of two band ratios, such as
, for the interstellar radiation conditions. We discuss on the applicability of the diagnostic diagram to other astronomical objects, comparing the LMC results with those observed in other galaxies such as NGC 6946, NGC 1313, and M51.
AKARI MID- TO FAR-INFRARED OBSERVATIONS OF DIFFUSE GALACTIC EMISSION
Sakon, I. ; Onaka, T. ; Mori, T.I. ; Ohsawa, R. ; Doi, Y. ; Okada, Y. ; Kaneda, H. ; Ootsubo, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 213~216
DOI : 10.5303/PKAS.2012.27.4.213
We have collected dozens of mid-infrared spectra showing UIR bands from diffuse Galactic emitting regions with the AKARI's Infrared Camera (IRC) onboard AKARI, as part of the ISMGN Mission Program. The datasets cover various directions in the inner Galactic Plane (
< 70 deg), in the outer Galactic Plane (
> 70 deg), and in the off-Plane (
> 2 deg). The variations in the UIR band ratios are examined in terms of the radiation environments judged from the far-infrared (
) spectral energy distribution (SED) made with AKARI/FIS All Sky Survey data at each slit position where mid-IR spectra were obtained. We have found that the band ratios of
toward the inner Galaxy are systematically higher than those toward the outer Galaxy and off the Galactic plane. Likely causes of the variations in properties of UIR bands in diffuse emission on a Galactic scale are discussed in this paper.
A STUDY OF THE GALACTIC CENTER REGIONS USING THE IMPROVED DATA OF THE MID-INFRARED ALL-SKY SURVEY
Mouri, A. ; Kaneda, H. ; Ishihara, D. ; Oyabu, S. ; Kondo, T. ; Suzuki, S. ; Yasuda, A. ; Onaka, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 217~218
DOI : 10.5303/PKAS.2012.27.4.217
Among the AKARI all-sky survey data, the
diffuse map is crucial to study the polycyclic aromatic hydrocarbon (PAH) emission features on large spatial scales, while the
map is useful to trace hot dust emission. To utilize these advantages, we have improved the AKARI mid-infrared (MIR) all-sky survey diffuse maps. For example, we have established special methods to remove the effects of the ionizing radiation in the South Atlantic Anomaly (SAA) and of the scattered light from the moon. Using improved diffuse map data, we study the properties of PAHs and dust in the Galactic center region associated with high-energy phenomena.
] AND [C
] DISTRIBUTIONS OF THE LARGE MAGELLANIC CLOUD WITH FIS-FTS
Takahashi, A. ; Yasuda, A. ; Kaneda, H. ; Kawada, M. ; Kiriyama, Y. ; Mouri, A. ; Mori, T. ; Okada, Y. ; Takahashi, H. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 219~220
DOI : 10.5303/PKAS.2012.27.4.219
We present the results of far-infrared spectroscopic observations of the Large Magellanic Cloud (LMC) with FIS-FTS. We covered a large area across the LMC, including 30 Doradus (30 Dor) and N44 star-forming regions, by 191 pointings in total. As a result, we detect the [OIII] and [CII] line emission as well as far-infrared dust continuum emission throughout the LMC. We find that the [OIII] emission is widely distributed around 30 Dor. The observed size of the distribution is too large to be explained by massive stars in 30 Dor, which are assumed to be enshrouded by clouds with the constant gas density estimated from the [OIII] line intensities. Therefore the surrounding structure is likely to be highly clumpy. We also find a global correlation between the [OIII] and the far-infrared continuum emission, suggesting that the gas and dust are well mixed in the highly-ionized region where the dust survives in clumpy dense clouds shielded from energetic photons. Furthermore we find that the ratios of [CII]/CO are as high as 110,000 in 30 Dor, and 45,000 even on average, while they are typically 6,000 for star-forming regions in our Galaxy. The unusually high [CII]/CO is also consistent with the picture of clumpy small dense clouds.
THE PROPERTIES OF DUST EMISSION IN THE GALACTIC CENTER REGION REVEALED BY FIS-FTS OBSERVATIONS
Yasuda, A. ; Kaneda, H. ; Takahashi, A. ; Nakagawa, T. ; Kawada, M. ; Okada, Y. ; Takahashi, H. ; Murakami, N. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 221~222
DOI : 10.5303/PKAS.2012.27.4.221
We present the results of far-infrared spectral mapping of the Galactic center region with FIS-FTS, which covered the two massive star-forming clusters, Arches and Quintuplet. We find that two dust components with temperatures of about 20 K and 50 K are required to fit the overall continuum spectra. The warm dust emission is spatially correlated with the [OIII]
emission and both are likely to be associated with the two clusters, while the cool dust emission is more widely distributed without any clear spatial correlation with the clusters. We find differences in the properties of the ISM around the two clusters, suggesting that the star-forming activity of the Arches cluster is at an earlier stage than that of the Quintuplet cluster.
INFRARED COMPOSITION OF THE LARGE MAGELLANIC CLOUD
Siudek, M. ; Pollo, A. ; Takeuchi, T.T. ; Ita, Y. ; Kato, D. ; Onaka, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 223~224
DOI : 10.5303/PKAS.2012.27.4.223
Understanding the birth and evolution of galaxies, and the history of star formation in them, is one of the most important problems in astronomy. Using the data from the AKARI IRC survey of the Large Magellanic Cloud at 3.2, 7, 11, 15, and
, we have constructed a multi-wavelength catalog containing data from the cross-correlation with a number of other databases at different wavelengths. We present the first approach with a Support Vector Machine (SVM)-based method to separate different classes of stars in LMC in the color-color and color-magnitude diagrams.
STARDUSTS IN SUPERNOVA REMNANTS SEEN BY AKARI
Koo, Bon-Chul ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 225~230
DOI : 10.5303/PKAS.2012.27.4.225
Supernovae (SN) and supernova remnants (SNRs) play a major role in the life-cycle of interstellar dusts. Fast shock waves generated by SN explosions sweep out the interstellar space destroying dust grains and modifying their physical and chemical properties. The dense, cooling SN ejecta, on the other hand, provide an environment for dusts to condense. Recent space-infrared telescopes have revealed the hidden universe related to these fascinating microscopic processes. In this paper, I introduce the results on stardusts in young core-collapse supernova remnants obtained by AKARI. The AKARI results show diverse infrared characteristics of stardusts associated with SNRs, implying diverse physical/chemical stellar structures and circumstellar environments at the time of explosion.
INFRARED SUPERNOVA REMNANTS IN THE LARGE MAGELLANIC CLOUD
Seok, J. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 231~234
DOI : 10.5303/PKAS.2012.27.4.231
We present preliminary results of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) seen by AKARI as well as Spitzer. By examining the AKARI LMC survey and the Spitzer data, we have searched for IR counterparts to 45 known SNRs in the LMC and could identify 28 SNRs with associated IR emission. 13 SNRs among them are newly detected in IR bands. For the entire IR SNRs, we make a catalog containing general information and the AKARI and/or Spitzer fluxes. Using the catalog, their IR colors and the possible correlation of the IR fluxes with the X-ray fluxes are examined. For some interesting SNRs, we have performed NIR spectroscopy with AKARI. An aromatic feature at
can be identified in LMC SNR N49. We investigate the characteristics of the IR features and discuss the PAH mission mechanism in SNRs.
SUPERNOVA REMNANTS IN THE AKARI FIS ALL-SKY SURVEY
Jeong, Il-Gyo ; Koo, Bon-Chul ; Lee, Ho-Gyu ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 235~236
DOI : 10.5303/PKAS.2012.27.4.235
We carry out a systematic study of Galactic supernova remnants (SNRs) using the AKARI Far Infrared Surveyor (FIS) survey data. The AKARI Infrared Astronomical Satellite observed the whole sky using the four FIS bands covering 50 to 180 microns with ~1 arcmin resolution. The all-sky coverage with high-spatial resolution provides an unprecedented opportunity to study diffuse, extended far-infrared (FIR) sources such as SNRs. We have searched for FIR counterparts to all 274 known Galactic SNRs, and investigate their FIR properties of identified SNRs. We report preliminary results of the study.
PROCESSING OF INTERSTELLAR DUST GRAINS IN GALAXIES
Kaneda, H. ; Ishihara, D. ; Onaka, T. ; Sakon, I. ; Suzuki, T. ; Kobata, K. ; Kondo, T. ; Yamagishi, M. ; Yasuda, A. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 237~242
DOI : 10.5303/PKAS.2012.27.4.237
We have performed a systematic study of interstellar dust grains in various environments of galaxies. AKARI has revealed the detailed properties of dust grains not only in star-forming regions but also in regions not relevant to star formation, some of which are found not to follow our old empirical knowledge. Because of its unique capabilities, AKARI has provided new knowledge on the processing of large grains and polycyclic aromatic hydrocarbons (PAHs). For example, we detect PAHs from elliptical galaxies, which show unusual spectral features and spatial distributions, demonstrating importance of material processing in the interstellar space. We find that copious amounts of large grains and PAHs are flowing out of starburst galaxies by galactic superwinds, which are being shattered and destroyed in galactic haloes. We discover evidence for graphitization of carbonaceous grains near the center of our Galaxy, providing a clue to understanding the activity of the Galactic center. We review the results obtained from our AKARI program, focusing on the processing of carbonaceous grains in various environments of galaxies.
OBSERVATIONS OF STAR FORMATION INDUCED BY GALAXY-GALAXY AND GALAXY-INTERGALACTIC MEDIUM INTERACTIONS WITH AKARI
Suzuki, T. ; Kaneda, H. ; Onaka, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 243~248
DOI : 10.5303/PKAS.2012.27.4.243
Nearby spiral galaxies M101 and M81 are considered to have undergone a galaxy-galaxy interaction. M101 has experienced HI gas infall due to the interaction. With AKARI far-infrared (IR) photometric observations, we found regions with enhanced star forming activity, which are spatially close to regions affected by the interaction. In addition, the relation between the star formation rate (SFR) and the gas content for such regions shows a significant difference from typical spiral arm regions. We discuss possible explanations for star formation processes on a kiloparsec scale and the association with interaction-triggered star formation. We also observed the compact group of galaxies Stephan's Quintet (SQ) with the AKARI Far-infrared Surveyor (FIS). The SQ shows diffuse intergalactic medium (IGM) due to multiple collisions between the member galaxies and the IGM. The intruder galaxy NGC 7318b is currently colliding with the IGM and causes a large-scale shock. The 160 micron image clearly shows the structure along the shock ridge as seen in warm molecular hydrogen line emission and X-ray emission. The far-IR emission from the shocked region comes from the luminous [CII]
line and cold dust (~ 20 K) that coexist with molecular hydrogen gas. Survival of dust grains is indispensable to form molecular hydrogen gas within the collision age (~ 5 Myr). At the stage of the dusty IGM environment, [CII] and
lines rather than X-ray emission are powerful cooling channels to release the collision energy.
SYSTEMATIC STUDY OF INTERSTELLAR ICES IN NEARBY GALAXIES
Yamagishi, M. ; Kaneda, H. ; Oyabu, S. ; Ishihara, D. ; Onaka, T. ; Shimonishi, T. ; Suzuki, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 249~252
DOI : 10.5303/PKAS.2012.27.4.249
The absorption features due to interstellar ices, especially
ices, provide us with crucial information on present and past interstellar environments, and thus the evolutionary histories of galaxies. Before AKARI, however, few detections of ices were reported for nearby galaxies. The AKARI's unique capability of near-infrared spectroscopy with high sensitivity enables us to systematically study ices in nearby galaxies. Thus we have explored many near-infrared spectra (
) of the 211 pointed observations, searching for the absorption features of ices. As a result, out of 122 nearby galaxies, we have significantly detected
ice from 36 galaxies and
ice from 9 galaxies. It is notable that the ices are detected not only in late-type galaxies but also in early-type galaxies. We find that
ice is more compactly distributed near the galactic center than
ice. Finally, we suggest that the gas density of a molecular cloud and UV radiation may be important factors to determine the abundance of ices.
INTERSTELLAR DUST IN M51 FROM IRC IMAGES
Egusa, Fumi ; Sakon, I. ; Onaka, T. ; Matsuhara, H. ; Arimatsu, K. ; Suzuki, T. ; Wada, T. ; The IRC team, The IRC team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 253~256
DOI : 10.5303/PKAS.2012.27.4.253
We present the IRC images of M51, a pair of interacting galaxies. Given the high angular resolution (7.4") and the wide field of view (~ 10') covering almost the entire M51 system, we investigate dust properties and their connection to the spiral arm structure. We have applied image-filtering processes including the wavelet analysis to the N3 image, which traces the total stellar mass best among the IRC bands. From this filtered image, the center, arm, and interarm regions are defined. A color, or flux ratio among the MIR bands, has been measured at each pixel (3.7" in size). We find a wide variety of S7/S11 with a difference between arm and interarm regions. We also find that at some positions S11 seems to be higher than predicted by MW dust models. Estimated contributions from the stellar continuum and gas emission lines to the band are not enough to explain this discrepancy. From these results, we deduce that the PAH ionization condition and its fraction to the total dust mass in M51 are different from those in MW.
THE CENTRAL REGION OF THE BARRED SPIRAL GALAXY NGC 1097 PROBED BY AKARI NEAR-INFRARED SPECTROSCOPY
Kondo, T. ; Kaneda, H. ; Oyabu, S. ; Ishihara, D. ; Mori, T. ; Yamagishi, M. ; Onaka, T. ; Sakon, I. ; Suzuki, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 257~258
DOI : 10.5303/PKAS.2012.27.4.257
With AKARI, we carried out near-infrared spectroscopy of the nearby barred spiral galaxy, NGC 1097, categorized as Seyfert 1 with a circumnuclear starburst ring. Our observations mapped the galactic center region. As a result, we obtain the spatial distributions of the polycyclic aromatic hydrocarbon
and the aliphatic hydrocarbon
emission. The former is detected from all the observed regions and the latter is enhanced near the bar connecting the ring with the nucleus. In addition, we detect absorption features due to
ice and CO/SiO at the ring and the galactic center, while we detect the hydrogen recombination line
only from the ring. Hence the observed spectra change dramatically within the central 1 kpc region.
INVESTIGATION OF PAHs IN GALACTIC PLANETARY NEBULAE WITH THE AKARI/IRC AND THE SPITZER/IRS
Ohsawa, R. ; Onaka, T. ; Sakon, I. ; Mori, T.I. ; Yamamura, I. ; Matsuura, M. ; Kaneda, H. ; Bernard-Salas, J. ; Berne, O. ; Joblin, C. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 259~260
DOI : 10.5303/PKAS.2012.27.4.259
Polycyclic aromatic hydrocarbons (PAHs) in Galactic planetary nebulae (PNe) are investigated by means of the unidentified infrared (UIR) bands. Continuous near- to mid-infrared spectra of PNe are obtained with the AKARI/IRC and the Spitzer/IRS. All 19 PNe in the present study show prominent dust emissions and we investigate the variation in the intensity ratios among the UIR bands. The ionization fraction and the size distribution of PAHs in PNe are derived using the UIR band ratios. We find that the ionization fraction of PAHs in PNe is around 0.0-0.6 and that small PAHs are scarce. The present result indicates a systematic trend of the
aliphatic feature to become weak as the PAH ionization fraction increases.
PATIAL DISTRIBUTION OF STAR FORMATION ACTIVITY ON NGC 253 BY FIR AND RADIO EMISSION LINES
Takahashi, H. ; Matsuo, H. ; Nakanishi, K. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 261~262
DOI : 10.5303/PKAS.2012.27.4.261
The aim of this research is to reveal the spatial distribution of the star formation activity of nearby galaxies by comparing CO molecular emission lines with the large area observation in far-infrared (FIR) lines. We report the imaging observations of NGC 253 by FIR forbidden lines via FIS-FTS and CO molecular lines from low to high excitation levels with ASTE, which are good tracers of star forming regions or photo-dissociation regions, especially spiral galaxies, in order to derive the information of the physical conditions of the ambient interstellar radiation fields. The combination of spatially resolved FIR and sub-mm data leads to the star formation efficiency within galaxy. The ratio between the FIR luminosity and molecular gas mass,
, is expected to be proportional to the number of stars formed in the galaxy per unit molecular gas mass and time. Moreover the FIR line ux shows current star formation activity directly. Furthermore these can be systematic and statistical data for star formation history and evolution of spiral galaxies.
PROPERTIES OF DUST IN EARLY-TYPE GALAXIES BASED ON THE ALL-SKY-SURVEY DATA AND NEAR-INFRARED SPECTRA
Mori, T. ; Oyabu, S. ; Kaneda, H. ; Ishihara, D. ; Yamagishi, M. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 263~264
DOI : 10.5303/PKAS.2012.27.4.263
We present the properties of dust and the near-infrared spectral features in nearby early-type galaxies. The properties of dust are obtained from the AKARI far-infrared all-sky survey diffuse map. The AKARI/IRC is used for the near-infrared spectra. We improve spectral data with the new dark subtraction method on the basis of the knowledge acquired in our laboratory experiments of the engineering-model detector for the IRC. We have succeeded in fitting the continuum by a power-law function and detecting CO and SiO absorption features in early-type galaxy spectra. Comparing the properties of dust and near-infrared spectral features, we find that the power-law slope depends on dust temperature, but not on the dust mass, which suggests that low-luminosity AGNs may contribute to the changes in the power-law slope and dust temperature.
SURVEY OF DUSTY ACTIVE GALACTIC NUCLEI BASED ON THE MID-INFRARED ALL-SKY SURVEY CATALOG
Oyabu, S. ; Ishihara, D. ; Yamada, R. ; Kaneda, H. ; Yamagishi, M. ; Toba, Y. ; Matsuhara, H. ; Nakagawa, T. ; Malkan, M. ; Shirahata, M. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 265~270
DOI : 10.5303/PKAS.2012.27.4.265
Many observations have found evidence of the presence of a large number of heavily obscured Active Galactic Nuclei (AGNs). However, the nature of this population is only poorly understood because heavy obscuration by dust prevents one from finding them at optical wavelengths. Mid-infrared AGN searches can overcome this obstacle by penetrating through dust and by detecting direct emission from the dust torus. Thus, we can identify most of the AGN population, including type-2 and buried AGNs. Using the AKARI mid-infrared all-sky survey, we performed an AGN search in the nearby universe. Utilizing the 2MASS photometry, we selected mid-infrared-excess sources and carried out near-infrared spectroscopic observations in the AKARI Phase 3. During these follow-up observations, we have found three galaxies that show strong near-infrared red continuum from hot dust with a temperature of about 500 K, but do not show any AGN features in other wavelengths. The most suitable explanation of near-infrared continuum is the presence of central AGNs. Therefore, we conclude that they are AGNs obscured by dust. We performed X-ray observations of the two galaxies with SUZAKU. No detections in the 0.4-10 keV suggest that the column density may be much higher than
. Comparing the masses of the host galaxies with those of the SDSS AGNs, we find that the host galaxies of the dusty AGNs discovered with AKARI are less massive populations than those of optically selected AGNs.
AKARI IRC INFRARED 2.5-5 ㎛ SPECTROSCOPY OF NEARBY LUMINOUS INFRARED GALAXIES
Imanishi, Masatoshi ; Nakagawa, Takao ; Shirahata, Mai ; Ohyama, Yoichi ; Onaka, Takashi ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 271~274
DOI : 10.5303/PKAS.2012.27.4.271
We present the result of systematic AKARI IRC infrared
spectroscopy of >100 nearby luminous infrared galaxies, to investigate the energetic roles of starbursts and optically-elusive buried AGNs. Based on (1) the equivalent widths of the
PAH emission features, (2) the optical depths of absorption features, and (3) continuum slopes, we can disentangle emission from starbursts and AGNs. We find that the energetic importance of buried AGNs increases with increasing galaxy infrared luminosities, suggesting that the AGN-starburst connections (and thereby possible AGN feedback to host galaxies) are luminosity dependent.
MID- AND FAR-INFRARED PROPERTIES OF LOCAL ACTIVE GALACTIC NUCLEI
Ichikawa, Kohei ; Ueda, Yoshihiro ; Terashima, Yuichi ; Oyabu, Shinki ; Gandhi, Poshak ; Matsuta, Keiko ; Nakagawa, Takao ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 275~279
DOI : 10.5303/PKAS.2012.27.4.275
We investigate the mid-infrared (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the infrared survey catalogs of AKARI, IRAS and WISE. Out of 135 non-blazar AGNs in the Swift/BAT 9-month catalog, we obtain the MIR photometric data for 128 sources in either the 9, 12, 18, 22, and
band. We find a good correlation between their hard X-ray and MIR luminosities ranging three orders of magnitude (42 < log
) < 45), which is tighter than that with the FIR luminosities at
. Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori models rather than homogeneous ones.
THE 3.3 ㎛ PAH FEATURE AS A SFR INDICATOR: PROBING THE INTERPLAY BETWEEN SF AND AGN ACTIVITIES
Kim, Ji Hoon ; Im, M. ; Kim, D. ; Woo, J.H. ; Park, D. ; Imanishi, M. ; AMUSES Team, AMUSES Team ; LQSONG Team, LQSONG Team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 281~284
DOI : 10.5303/PKAS.2012.27.4.281
We utilize AKARI's slitless spectroscopic capability to detect the
polycyclic aromatic hydrocarbons (PAHs) emission and measure star formation (SF) activity for various AKARI programs. First, we obtain
spectra of 20 flux-limited galaxies with mixed SED classes in order to calibrate the
PAH luminosity (
) as a star formation rate (SFR) indicator. We find that
as well as with the
PAH luminosity (
). The correlations does not depend on SED classes. We find that ULIRGs deviate from the correlation between PAH luminosities and
, while they do not for the correlation between PAH luminosities. We suggest possible effects to cause this deviation. On the other hand, how AGN activity is linked to SB activity is one of the most intriguing questions. While it is suggested that AGN luminosity of quasars correlates with starburst (SB) luminosity, it is still unclear how AGN activity is connected to SF activity based on host galaxy properties. We are measuring SFRs for the LQSONG sample consisting of reverberation mapped AGNs and PG-QSOs. This is an extension of the ASCSG program by which we investigated the connection between SB and AGN activities for Seyferts type 1s at z ~ 0.36. While we found no strong correlation between
and AGN luminosity for these Seyferts 1s,
measured from the central part of galaxies correlates with AGN luminosity, implying that SB and AGN activities are directly connected in the nuclear region.
INFRARED AND HARD X-RAY DIAGNOSTICS OF AGN IDENTIFICATION FROM THE AKARI AND SWIFT/BAT ALL-SKY SURVEYS
Matsuta, K. ; Gandhi, P. ; Dotani, T. ; Nakagawa, T. ; Isobe, N. ; Ueda, Y. ; Ichikawa, K. ; Terashima, Y. ; Oyabu, S. ; Yamamura, I. ; Stawarz, L. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 285~286
DOI : 10.5303/PKAS.2012.27.4.285
We combine data from two all-sky surveys, the Swift/Burst Alert Telescope 22 Month Source Catalog and the AKARI Point Source Catalogue, in order to study the connection between the hard X-ray (> 10 keV) and infrared (IR) properties of local active galactic nuclei (AGN). We find two photometric diagnostics are useful for source classification: one is the X-ray luminosity vs. IR color diagram, in which type 1 radio-loud AGN are well isolated from other AGN. The second one uses the X-ray vs. IR color-color diagram as a redshift-independent indicator for identifying Compton-thick (CT) AGN. Importantly, CT AGN and starburst galaxies in composite systems can also be separated in this plane based upon their hard X-ray fluxes and dust temperatures. This diagram may be useful as a new indicator to classify objects in new surveys such as with WISE and NuSTAR.
RADIO-AGN IN THE AKARI-NEP FIELD AND THEIR ROLE IN THE EVOLUTION OF GALAXIES
Karouzos, M. ; Im, M. ; The Akari-Nep Team, The Akari-Nep Team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 287~288
DOI : 10.5303/PKAS.2012.27.4.287
Radio-loud active galaxies have been found to exhibit a close connection to galactic mergers and host galaxy star-formation quenching. We present preliminary results of an optical spectroscopic investigation of the AKARI NEP field. We focus on the population of radio-loud AGN and use photometric and spectroscopic information to study both their star-formation and nuclear activity components. Preliminary results show that radio-AGN are associated with early type, massive galaxies with relatively old stellar populations.
DUST-OBSCURED RADIO AGNS FROM THE WISE SURVEY
Kim, Minjin ; Lonsdale, Carol J. ; Lacy, Mark ; Kimball, Amy ; Condon, Jim ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 289~290
DOI : 10.5303/PKAS.2012.27.4.289
Feedback from accreting BH (AGN) is thought to be responsible for the co-evolution of BHs and galaxies. It is likely to be prominent in the most luminous dust-obscured quasars, particularly those containing radio sources too luminous to be powered by starbursts. In order to investigate the feedback mechanism in detail, we select a unique sample containing ~ 200 of the most luminous obscured QSOs by cross-matching the WISE catalog with the FIRST and NVSS radio surveys. We present overall statistics for the observed range of colors and radio/mid-IR flux density ratio. We also present our efforts to understand the physical and evolutionary nature of these extreme feedback candidates using various telescopes such as Magellan, SOAR, Herschel, and ALMA.
SED DECOMPOSITION OF INFRARED-LUMINOUS GALAXIES
Lee, Jong Chul ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 291~292
DOI : 10.5303/PKAS.2012.27.4.291
We select infrared-luminous galaxies by cross-matching the SDSS spectroscopic sample of galaxies with the WISE all-sky survey catalog. Based on photometric data points covering from SDSS u-band to WISE
, their spectral energy distributions (SEDs) are separated into AGN, elliptical, spiral, and irregular galaxy components. The derived luminosities of spiral galaxy and AGN are well correlated with
and [OIII] line luminosities, respectively. Most galaxies are dominated by young stellar populations even for optical AGNs, but at least 10% of optical non-AGNs appear to harbor buried AGNs. The AGN contribution increases dramatically with the total luminosity. These results show that the SED decomposition is successful and is useful to understand the true nature of dusty galaxies.
CLASSIFICATION SCHEMES AND PROPERTIES OF INFRARED GALAXIES
Rybka, P. ; Pollo, A. ; Takeuchi, T.T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 293~294
DOI : 10.5303/PKAS.2012.27.4.293
We established a separation scheme to distinguish galaxies from stars with the aid of AKARI/FIS color-color (CC) diagrams. In all the combinations of CC diagrams we can distinguish two separate clouds. It was shown that in all cases one of them contains more than 95% of galaxies and the other one, in most cases, consists in more than 80% of stars (Pollo et al., 2010). Currently we are looking into more detailed classifications. We are especially interested in separating different morphological types of galaxies, mainly within spiral galaxies. Moreover, we study the properties of infrared galaxies.
NEAR-INFRARED HIGH-RESOLUTION SPECTROSCOPY OF THE OBSCURED AGN IRAS 01250+2832
Shirahata, M. ; Usuda, T. ; Oyabu, S. ; Nakagawa, T. ; Yamamura, I. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 295~296
DOI : 10.5303/PKAS.2012.27.4.295
We provide a new physical insight on the hot molecular clouds near the nucleus of the heavily obscured AGN IRAS 01250+2832, based on the results of near-infrared high-resolution spectroscopy of gaseous CO ro-vibrational absorption lines with Subaru/IRCS. The detected CO absorption lines up to highly excited rotational levels reveal that hot dense molecular clouds exist around the AGN under the peculiar physical conditions.
miniTAO/ANIR Paα SURVEY OF LOCAL LIRGs
Tateuchi, Ken ; Motohara, Kentaro ; Konishi, Masahiro ; Takahashi, Hidenori ; Kato, Natsuko ; Uchimoto, Yuka K. ; Toshikawa, Koji ; Ohsawa, Ryou ; Kitagawa, Yutaro ; Yoshii, Yuzuru ; Doi, Mamoru ; Kohno, Kotaro ; Kawara, Kimiaki ; Tanaka, Masuo ; Miyata, Takashi ; Tanabe, Toshihiko ; Minezaki, Takeo ; Sako, Shigeyuki ; Morokuma, Tomoki ; Tamura, Yoichi ; Aoki, Tsutomu ; Soyano, Takeo ; Tarusawa, Kenfichi ; Koshida, Shintaro ; Kamizuka, Takafumi ; Nakamura, Tomohiko ; Asano, Kentaro ; Uchiyama, Mizuho ; Okada, Kazushi ; Ita, Yoshifusa ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 297~298
DOI : 10.5303/PKAS.2012.27.4.297
ANIR (Atacama Near InfraRed camera) is a near infrared camera for the University of Tokyo Atacama 1m telescope, installed at the summit of Co. Chajnantor (5,640 m altitude) in northern Chile. The high altitude and extremely low water vapor (PWV = 0.5 mm) of the site enable us to perform observation of hydrogen
emission line at
. Since its first light observation in June 2009, we have been carrying out a
narrow-band imaging survey of nearby luminous infrared galaxies (LIRGs), and have obtained
for 38 nearby LIRGs listed in AKARI/FIS-PSC at the velocity of recession between 2,800 km/s and 8,100 km/s. LIRGs are affected by a large amount of dust extinction (
~ 3 mag), produced by their active star formation activities. Because
is the strongest hydrogen recombination line in the infrared wavelength ranges, it is a good and direct tracer of dust-enshrouded star forming regions, and enables us to probe the star formation activities in LIRGs. We find that LIRGs have two star-forming modes. The origin of the two modes probably come from differences between merging stage and/or star-forming process.
THE 3.3 MICRON PAH EMISSION OF THE MID-INFRARED EXCESS GALAXIES DISCOVERED BY THE AKARI MID-INFRARED ALL-SKY SURVEY
Yamada, R. ; Oyabu, S. ; Kaneda, H. ; Yamagishi, M. ; Ishihara, D. ; Kim, J.H. ; Im, M. ; Toba, Y. ; Matsuhara, H. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 299~300
DOI : 10.5303/PKAS.2012.27.4.299
We investigate the relation between star formation activity and PAH
emission. Our targets are mid-infrared-excess galaxies selected from the AKARI all-sky survey point source catalog. We performed AKARI near-infrared spectroscopy for them. As a result, we obtained
spectra of 79 galaxies, and selected 35 star-forming galaxies out of them. Comparing the PAH
luminosities with the infrared luminosities, we find a linear correlation between them. However, by adding the results from literatures for luminous infrared galaxies and ultra-luminous infrared galaxies that are more luminous than our sample, the ratio of the PAH to the infrared luminosity is found to decrease towards the luminous end.
EVOLUTION OF LUMINOUS INFRARED GALAXIES REVEALED BY NEAR-INFRARED MULTI-BAND IMAGING OF THEIR HOSTS
Oi, Nagisa ; Imanishi, Masatoshi ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 301~303
DOI : 10.5303/PKAS.2012.27.4.301
We present the result of our near infrared J- (
), H- (
) imaging of ultraluminous (
) and luminous (
) infrared galaxies (ULIRGs and LIRGs), to investigate their relationship through properties of their host galaxies. We find that (1) for single-nucleus ULIRGs and LIRGs, their spheroidal host galaxies have similar properties, but ULIRGs display a substantially higher level of nuclear activity than LIRGs, suggesting that their infrared luminosity difference comes primarily from the different level of current nuclear activity. We infer that LIRGs and ULIRGs have similar progenitor galaxies, follow similar evolutionary processes, and may evolve into optically-selected QSOs. (2) Largely-separated multiple-nuclei ULIRGs have significantly brighter host galaxies than single-nucleus ULIRGs and LIRGs in
-band, indicating that multiple-nuclei ULIRGs have a bias towards mergers of intrinsically large progenitor galaxies, in order to produce high infrared luminosity (
) even at the early merging stage. (3) We derive dust extinction of host galaxies of ULIRGs and LIRGs to be
~ 14 mag in the optical or equivalently
~ 0.8 mag in the near-infrared
-band, based on the comparison of host galaxy's luminosities in the J-, H-, and
A MULTI-WAVELENGTH VIEW OF GALAXY EVOLUTION WITH AKARI
Serjeant, S. ; Pearson, C. ; White, G.J. ; Smith, M.W.L. ; Doi, Y. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 305~310
DOI : 10.5303/PKAS.2012.27.4.305
AKARI's all-sky survey resolves the far-infrared emission in many thousands of nearby galaxies, providing essential local benchmarks against which the evolution of high-redshift populations can be measured. This review presents some recent results in the resolved galaxy populations, covering some well-known nearby targets, as well as samples from major legacy surveys such as the Herschel Reference Survey and the JCMT Nearby Galaxies Survey. This review also discusses the prospects for higher redshifts surveys, including strong gravitational lens clusters and the AKARI NEP field.
GALAXY SED FITTING FROM AKARI TO HERSCHEL: 0.7 < z < 4 SUB-MILLIMETER LYMAN BREAK GALAXIES IN INFRARED
Burgarella, D. ; The PEP-HerMES-COSMOS team, The PEP-HerMES-COSMOS team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 311~316
DOI : 10.5303/PKAS.2012.27.4.311
Lyman break Galaxies are galaxies selected in the rest-frame ultraviolet. But, one important and missing information for these Lyman break galaxies is the amount of dust attenuation. This is crucial to estimate the total star formation rate of this class of objects and, ultimately, the cosmic star formation density. AKARI, Spitzer and Herschel are therefore the major facilities that could provide us with this information. As part of the Herschel Multi-tiered Extragalactic Survey, we have began investigating the rest-frame far-infrared properties of a sample of more than 4,800 Lyman Break Galaxies in the GOODS-North fiels. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z <1.6 and one object at z = 2.0. The ones detected by Herschel SPIRE have redder observed NUV-U and U-R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. We have analysed their UV-to-FIR spectral energy distributions using the code cigale to estimate their physical parameters. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. They also appear to be located in a triangle-shaped region in the
diagram limited by
= 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. In a second step, we move to the larger COSMOS field where we have been able to detect 80 Lyman break galaxies (out of ~ 15,600) in the far infrared. They form the largest sample of Lyman break galaxies at z > 2.5 detected in the far-infrared. We tentatively name them Submillimeter Lyman break galaxies (S-LBGs).
AKARI-SDSS-GALEX SURVEYS: SPECTRAL ENERGY DISTRIBUTIONS OF NEARBY GALAXIES
Buat, V. ; Yuan, F.T. ; Takeuchi, T.T. ; Giovannoli, E. ; Heinis, S. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 317~320
DOI : 10.5303/PKAS.2012.27.4.317
A sample of nearby galaxies was built from the AKARI/FIS all sky survey cross-correlated with the SDSS and GALEX surveys. The spectral energy distributions from 0.15 to 160 microns of these galaxies are analysed to study dust attenuation and star formation properties. The calibrations of the amount of dust attenuation as a function of the IR-to-UV flux ratio and the FUV-NUV colour are re-investigated: the former one is confirmed to be robust and accurate whereas the use of the FUV-NUV colour to measure dust attenuation is found highly uncertain. The current star formation rate given by the SED fitting process is compared to that directly obtained from the UV and total IR luminosities. It leads to an accurate estimate of dust heating by old stars. We emphasize the importance of such a sample as a reference for IR selected star forming galaxies in the nearby universe.
A MULTI-WAVELENGTH STUDY OF PAH-SELECTED STARBURST GALAXIES
Takagi, T. ; Matsuhara, H. ; Wada, T. ; Ohyama, Y. ; Oyabu, S. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 321~324
DOI : 10.5303/PKAS.2012.27.4.321
Using extensive mid-IR datasets from AKARI, i.e. 9-band photometry covering the wavelength range from
and the unbiased spectroscopic survey for sources with
)>0.3 mJy, we study starburst galaxies specifically at the redshift of z ~ 0.5, whose mid-IR spectra are clearly dominated by the PAH emission features. PAH-selected galaxies, selected with extremely red mid-IR colour due to PAHs, have high rest-frame PAH-to-stellar luminosity ratios, comparable to those in the most active regions in nearby starburst galaxies. Thus, they seem to have active starburst regions spreading over the whole body. Furthermore, some of PAH-selected galaxies are found to have peculiar rest-frame 11-to-
flux ratios, which is systematically smaller than nearby starburst/AGN spectral templates. This may indicate a systematic difference in the physical condition of ISM between nearby and distant starburst galaxies.
INFRARED SPECTRAL ENERGY DISTRIBUTION OF GALAXIES IN THE AKARI ALL SKY SURVEY: CORRELATIONS WITH GALAXY PROPERTIES AND THEIR PHYSICAL ORIGIN
Makiya, R. ; Totani, T. ; Takeuchi, T.T. ; Nagashima, M. ; Kobayashi, M.A.R. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 325~329
DOI : 10.5303/PKAS.2012.27.4.325
We will report our recent study on the properties of more than 1,600 galaxies detected by the AKARI All-Sky Survey with physical quantities based on optical and 21-cm observations, to understand the physics determining the infrared spectral energy distribution (Totani et al., 2011). We discover a tight linear correlation for normal star-forming galaxies between the radiation field strength of dust heating (corresponding to dust temperature) and the galactic-scale infrared radiation field,
. This is the tightest correlation of dust temperature ever known, and the dispersion along the mean relation is 13% in dust temperature. This relation can be explained physically by a thin layer of heating sources embedded in a thicker, optically-thick dust screen. We also find that the number of galaxies sharply drops when galaxies become optically thin against dust-heating radiation, indicating that a feedback process to galaxy formation (e.g., by the photoelectric heating) is working when dust-heating radiation is not self-shielded on a galactic scale. We discuss implications from these findings for the
-size relation, the Kennicutt-Schmidt relation, and galaxy formation in the cosmological context.
ENVIRONMENTAL DEPENDENCE OF STAR FORMATION AND GALAXY TRANSFORMATION IN MERGING GALAXY CLUSTER ABELL 2255: AKARI'S POINT OF VIEW
Shim, Hyunjin ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 331~334
DOI : 10.5303/PKAS.2012.27.4.331
We investigate the role of galaxy environment in the evolution of individual galaxies through the AKARI observations of the merging galaxy cluster A2255. MIR diagnostics using N3-S11 colors are adopted to select star-forming galaxies and galaxies in transition between star-forming galaxies and quiescent galaxies. We do not find particular enhancement of star formation rates as a function of galaxy environment, reflected in cluster-centric distance and local surface density of galaxies. Instead, the locations of intermediate MIR-excess galaxies (-1.2 < N3 - S11 < 0.2) show that star-forming galaxies are transformed into passive galaxies in the substructures of A2255, where the local surface density of galaxies is relatively high.
THE 18 ㎛ LUMINOSITY FUNCTION OF GALAXIES WITH AKARI
Toba, Yoshiki ; Oyabu, Shinki ; Matsuhara, Hideo ; Ishihara, Daisuke ; Malkan, Matt ; Wada, Takehiko ; Ohyama, Youichi ; Kataza, Hirokazu ; Takita, Satoshi ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 335~338
DOI : 10.5303/PKAS.2012.27.4.335
We present the
luminosity function (LF) of galaxies at 0.006 < z < 0.8 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected 243 galaxies at
from the Sloan Digital Sky Survey (SDSS) spectroscopic region. These galaxies then have been classified into five types; Seyfert 1 galaxies (Sy1, including quasars), Seyfert 2 galaxies (Sy2), low ionization narrow emission line galaxies (LINER), galaxies that are likely to contain both star formation and Active Galactic Nuclei (AGN) activities (composites), and star forming galaxies (SF) using optical emission lines such as the line width of
or the emission line ratios of [OIII]/
. As a result of constructing the LF of Sy1 and Sy2, we found the following results; (i) the number density ratio of Sy2 to Sy1 is
, larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with
luminosity. These results suggest that most of the AGNs in the local universe are obscured by dust and the torus structure probably depends on the mid-infrared luminosity.
RADIO EMISSION FROM AKARI GALAXIES
Pepiak, A. ; Solarz, A. ; Pollo, A. ; Takeuchi, T.T. ; Jurusik, W. ; AKARI Team, AKARI Team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 339~341
DOI : 10.5303/PKAS.2012.27.4.339
It is a long known fact that there exists a tight correlation between far-infrared and radio emission both for galaxies hosting active galactic nuclei and for star forming galaxies. We probe the radio - infrared correlation for a sample of extragalactic sources constructed by the cross-correlation of the AKARI/IRC All-Sky Survey Point Source Catalogue, the AKARI/FIS All-Sky Survey Bright Source Catalogue, and the NRAO VLA Sky Survey. Additionally, all objects of our sample were identified as galaxies in NED and SIMBAD databases, and a part of them is known to host active galactic nuclei (AGNs). After remeasuring all the fluxes, in order to avoid small aperture effects, we compare the ratio of radio to infrared emission from different types of extragalactic sources, and discuss the FIR/radio correlation as seen by AKARI and make a comparison to the previous results obtained thanks to IRAS.
ANGULAR CLUSTERING OF FIR-SELECTED GALAXIES IN THE AKARI ALL-SKY SURVEY
Pollo, A. ; Takeuchi, T.T. ; Suzuki, T.L. ; Oyabu, S. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 343~344
DOI : 10.5303/PKAS.2012.27.4.343
We present the first measurement of the angular two-point correlation function for AKARI
point sources, detected outside of the Milky Way plane and selected as candidates for extragalactic sources. This is the first measurement of the large-scale angular clustering of galaxies selected in the far-infrared after IRAS. We find a positive clustering signal in both hemispheres extending up to ~ 40 degrees, without any significant fluctuations at larger scales. The observed correlation function is well fitted by a power law function. However, southern galaxies seem to be more strongly clustered than northern ones and the difference is statistically significant. The reason for this difference - technical or physical - is still to be found.
STAR FORMATION RATE CALIBRATIONS FOR WISE LUMINOSITIES
Yuan, F.T. ; Takeuchi, T.T ; Buat, V. ; Burgarella, D. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 345~346
DOI : 10.5303/PKAS.2012.27.4.345
Starting from an infrared selected GALEX-SDSS-2MASS-AKARI sample of local star forming galaxies, we built mock samples from redshift 0 to 2.5 to investigate star formation rate (SFR) calibrations using WISE luminosities. We find W3 and W4 band fluxes can indicate SFRs with small scatters when the rest-frame wavelengths are longer than
. When the wavelength becomes shorter, the observed luminosities are more tightly connected to the emission of old stellar populations than dust, therefore lose the reliability to trace the SFR. The current SFR calibrations are consistent with previous studies.
COSMIC STAR FORMATION HISTORY AND AGN EVOLUTION NEAR AND FAR: AKARI REVEALS BOTH
Goto, Tomotsugu ; AKARI NEP team, AKARI NEP team ; AKARI all sky survey team, AKARI all sky survey team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 347~352
DOI : 10.5303/PKAS.2012.27.4.347
Understanding infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe this both at low and high redshifts. The AKARI performed an all sky survey in 6 IR bands (9, 18, 65, 90, 140, and
) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can measure the total infrared luminosity (
) of individual galaxies much more precisely, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe
, and total infrared (TIR) luminosity functions (LFs) at 0.15 < z < 2.2 using 4,128 infrared sources. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and
) by the AKARI satellite allows us to estimate restframe
luminosities without using a large extrapolation based on a SED fit, which was the largest uncertainty in previous work. By combining these two results, we reveal dust-hidden cosmic star formation history and AGN evolution from z = 0 to z = 2.2, all probed by the AKARI satellite.
FAR-IR GALACTIC EMISSION MAP AND COSMIC OPTICAL BACKGROUND
Matsuoka, Y. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 353~356
DOI : 10.5303/PKAS.2012.27.4.353
We present new constraints on the cosmic optical background (COB) obtained from an analysis of the Pioneer 10/11 Imaging Photopolarimeter (IPP) data. After careful examination of the data quality, the usable measurements free from the zodiacal light are integrated into sky maps at the blue (
) and red (
) bands. Accurate starlight subtraction was achieved by referring to all-sky star catalogs and a Galactic stellar population synthesis model down to 32.0 mag. We find that the residual light is separated into two components: one component shows a clear correlation with the thermal
brightness, whilst the other shows a constant level in the lowest
brightness region. The presence of the second component is significant after all the uncertainties and possible residual light in the Galaxy are taken into account, thus it most likely has an extragalactic origin (i.e., the COB). The derived COB brightness is (
in the blue and red spectral regions, respectively, or
. Based on a comparison with the integrated brightness of galaxies, we conclude that the bulk of the COB is comprised of normal galaxies which have already been resolved by the current deepest observations. There seems to be little room for contributions from other populations including "first stars" at these wavelengths. On the other hand, the first component of the IPP residual light represents the diffuse Galactic light (DGL)-scattered starlight by the interstellar dust. We derive the mean DGL-to-
brightness ratios of
at the two bands, which are roughly consistent with previous observations toward denser dust regions. Extended red emission in the diffuse interstellar medium is also confirmed.
DETECTION OF Hα EMISSION FROM z>3.5 GALAXIES WITH AKARI-FUHYU NIR SPECTROSCOPY
Sedgwick, Chris ; Serjeant, Stephen ; Pearson, Chris ; Takagi, Toshinobu ; Matsuhara, Hideo ; Wada, Takehiko ; Lee, Hyung Mok ; Im, Myungshin ; Jeong, Woong-Seob ; Oyabu, Shinki ; White, Glenn J. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 357~360
DOI : 10.5303/PKAS.2012.27.4.357
This paper presents
emission line detections for four galaxies at z > 3.5 made with AKARI as part of the FUHYU mission program. These are the highest-redshift
detections to date in star-forming galaxies. AKARI's unique near-infrared spectroscopic capability has made these detections possible. For two of these galaxies, this represents the first evidence of their redshifts and confirms their physical association with a companion radio galaxy. The star formation rates (SFRs) estimated from the
lines under-predict the SFRs estimated from their far-infrared luminosities by a factor of ~ 2 - 3. We have also detected broad
components in the two radio galaxies which indicate the presence of quasars.
BLACK HOLE MASS MEASUREMENTS WITH REST-FRAME OPTICAL QUASAR SPECTRA AT 3
Jun, Hyunsung David ; Im, Myungshin ; Lee, Hyung Mok ; AKARI QSONG team, AKARI QSONG team ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 361~362
DOI : 10.5303/PKAS.2012.27.4.361
We summarize the progress on the rest-frame optical spectroscopy of quasars at 3
. This spectral window has been utilized for detecting redshifted
emission lines of our high redshift subsample of quasars. From the calculated emission line widths and luminosities we measured supermassive black hole masses using well calibrated optical mass estimators. Science topics regarding optical based black hole masses at high-z are discussed.
AKARI OBSERVATION OF THE FLUCTUATION OF THE NEAR-INFRARED BACKGROUND
Matsumoto, T. ; Seo, H.J. ; Jeong, W.S. ; Lee, H.M. ; Matsuura, S. ; Matsuhara, H. ; Oyabu, S. ; Pyo, J. ; Wada, T. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 363~365
DOI : 10.5303/PKAS.2012.27.4.363
We report a search for fluctuations of the sky brightness toward the North Ecliptic Pole with AKARI, at 2.4, 3.2, and
. The stacked images with a diameter of 10 arcminutes of the AKARI-Monitor Field show a spatial structure on the scale of a few hundred arcseconds. A power spectrum analysis shows that there is a significant excess fluctuation at angular scales larger than 100 arcseconds that cannot be explained by zodiacal light, diffuse Galactic light, shot noise of faint galaxies, or clustering of low-redshift galaxies. These findings indicate that the detected fluctuation could be attributed to the first stars of the universe, i.e., Population III stars.
WISE AND AKARI
Blain, Andrew W. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 367~373
DOI : 10.5303/PKAS.2012.27.4.367
The first all-sky mid-/far-infrared survey by IRAS in the 1980s, has been followed by only two more, by AKARI, from 2006, and WISE in 2010. I discuss some features of the WISE survey, and highlight some key results from early extragalactic observations that have been made by the science team during the operation of the telescope, and the post-operation proprietary period during which the public release data products were being generated. The efficient survey strategy and very high-data rate from WISE produced a catalogue of 530 million objects that was released to the public in March 2012. The WISE survey strategy naturally provided the deepest coverage at the ecliptic poles, where matched comparison fields were obtained using Spitzer, and where AKARI also observed deep fields. I describe some of the follow-up work that has been carried out based on the WISE survey, and the prospects for enhancing the WISE data by combining the AKARI survey results are also discussed. While the all-sky AKARI survey is less deep than the WISE catalogue, and is still being worked on by the AKARI science team, it includes a larger number of bands, extends to longer wavelengths, and in particular has very complementary band passes to WISE in the mid-infrared waveband, which will provide enhanced spectral information for relatively bright targets.
THE SYNERGY OF LARGE AREA SURVEYS WITH AKARI AND HERSCHEL
Pearson, Chris ; Serjeant, Stephen ; Sedgwick, Chris ; White, Glenn J. ; Matsuhara, Hideo ; Takagi, Toshinobu ; Nagisa, Oi ; Murata, Kazumi ; Nakagawa, Takao ; Yamamura, Issei ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 375~380
DOI : 10.5303/PKAS.2012.27.4.375
The Herschel Space Observatory is the European Space Agency's state of the art infrared space telescope launched into space on 14 May 2009, covering the wavelength range from 70-700 microns with 3 instruments SPIRE, PACS and HIFI. Large area surveys are being carried out by Herschel in the AKARI legacy fields at the North and South Ecliptic Poles and the AKARI All-Sky Survey provides additional synergy with the largest survey with Herschel, H-ATLAS, covering more than 500 square degrees. This paper reports on some of the early results of these synergies between Herschel and AKARI including the first comparison of the AKARI All-Sky Survey number counts with the deeper Herschel surveys.
SYNERGY BETWEEN IRSF AND AKARI
Nagayama, T. ; Kokusho, T. ; Kaneda, H. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 381~382
DOI : 10.5303/PKAS.2012.27.4.381
InfraRed Survey Facility (IRSF) is our facility for near-infrared (NIR) observation located at South African Astronomical Observatory. The NIR camera SIRIUS on the 1.4m telescope provides three
images in the J (
), H (
) bands simultaneously with a pixel scale of 0.45". IRSF has three unique capabilities, which are suitable for follow-up observations of AKARI-selected objects. Several synergistic studies with AKARI are in progress from stars to galaxies. We introduce advantages of the above unique capabilities of IRSF for further synergistic studies between AKARI and IRSF.
CONFERENCE SUMMARY: THE LEGACY OF AKARI: A PANORAMIC VIEW OF THE DUSTY UNIVERSE
White, Glenn J. ;
Publications of The Korean Astronomical Society, volume 27, issue 4, 2012, Pages 383~389
DOI : 10.5303/PKAS.2012.27.4.383
This report presents a summary of the Legacy of AKARI: A Panoramic View of the Dusty Universe meeting held between 27-29th February 2012 at Jeju Island, South Korea.